1. Field of the Invention
The present invention generally relates to an apparatus for applying flocking fibers to an article. More specifically, this invention relates to an apparatus and a method carried out by the apparatus for bonding flocking fibers to intricate three dimensional articles, such as metal clips used to join two or more objects, in which the adhesive strength between the flocking fibers and the article is sufficient for automotive use.
2. Description of the Prior Art
Various forms of clips are widely known in the fastener art, with the primary common feature being the ease by which the clip can be installed to assemble two or more objects without the need for additional cooperating components. In their most common form, clips are of the spring clip type which are self-retaining, one-piece fasteners having a spring feature for resiliently engaging a mounting hole or flange. Spring tension created between the spring feature and the mounting hole or flange secures the clip and enables the clip to resist loosening due to vibration.
Spring clips are often preferred where cost and quick assembly is of primary importance. In the case of a spring clip which engages a mounting hole, spring clips are particularly attractive where disassembly is rarely or never required. A common example of such an application is where a panel is to be secured to a frame, such as an automotive instrument panel which is mounted to the interior of an automobile. The spring clip is typically attached to the inner surface of the panel, and then forcibly inserted into a mounting hole provided in the support structure for the panel. The support structure will generally be a relatively thin but rigid member such that the mounting hole is a through hole with minimal depth. Once the clip is inserted into the mounting hole, the spring feature, which is often one or more cantilevered members projecting from the main body of the clip, engages the opposite surface of the mounting structure to retain the panel to the structure.
While clips have been widely accepted in such automotive applications, two related problems have generally been encountered. The first is the tendency for a clip to result in a somewhat loose assembly, the spring tension provided by the spring feature being insufficient to secure the panel tightly to the support structure. This is due in part to the second encountered problem, that being the need to provide sufficient clearance between the clip and its mounting hole to allow for assembly with minimal effort. As the ease of installation increases, there is typically a corresponding decrease in the clip's ability to tightly secure the panel to the support structure. Associated with this deficiency is the noise produced between the panel, the clip and the support structure when the assembly is subjected to vibration. In contrast, where a clip fits sufficiently tight within the mounting hole to minimize noise due to vibration, there is a corresponding increase in the difficulty in which the clip is inserted into the mounting hole. Consequently, under high volume, mass production conditions there arises a significant increase in deformed and damaged clips.
As a solution, the prior art has applied flocking technology to ease the assembly of the clip into its corresponding hole while maintaining a close fit therebetween. Generally, a flocking process entails the bonding of numerous short fibers to a surface such that each fiber projects substantially perpendicular from the surface. Common fiber materials include textile fibers, such as cotton, and synthetics, such as polyesters, depending upon the environment in which the flocking is intended to perform. As applied to a spring clip, the flocking fibers act to ease the assembly of the spring clip with the mounting hole in the support structure, while also acting to dampen vibration between the panel and the mounting hole to reduce noise.
Numerous examples of flocking apparatuses and processes, along with uses for flocking fibers, are taught in the art. Examples of flocking apparatuses include U.S. Pat. No. 4,146,177 to Jordan et al U.S Pat. No. 4,420,360 to Batisse, U.S. Pat. No. 4,879,969 to Haranoya et al, and U.S. Pat. No. 4,963,392 to Molnar et al. Each apparatus has as its primary object the ability to efficiently and broadly distribute the flocking material over the target surface. Consequently, the apparatuses of the prior art generally require space sufficient to allow the flocking fibers to disperse during the flocking process. Each apparatus also provides a method for electrostatically charging the flocking fibers and the target surface prior to introducing the fibers to the target. The fibers and the target surface are oppositely charged such that fibers are attracted to the target, where they adhere to an adhesive previously applied to the target surface. Though often noted that the flocking material need not be electrostatically attracted to the target surface, this processing method is generally preferred, as can be seen by the above-noted patents.
The prior art teaches that articles of various materials can be flocked using the electrostatic method, as seen by U.S. Pat. No. 5,047,103 to Abrams et al, U.S. Pat. No. 4,746,546 to Bachmann et al, and Batisse, which teach the flocking of cloth fabrics, plastics, and metals, respectively. Moreover, the electrostatic method is adaptable for flocking articles of various sizes and shapes, as suggested by U.S. Pat. No. 4,238,526 to Chitouras.
However, considerable difficulty has been encountered with attempts to flock intricate articles such as the spring clips described above. Because of the typically complicated forms which spring clips require, so as to provide a spring feature and a mounting feature by which the clip is attached to a panel, uniformity of the flocking material is difficult to attain. In addition, problems of adherence between the flocking fibers and the spring clip have also been encountered because of the sharp bends often formed in the clip. As a result, the art pertaining to spring clips presently employs pliant strips of cloth or plastic to which the flocking fibers are first adhered. The strips are then cut to size and adhered to the surfaces of the clips where friction can be reduced to improve assembly ease and where dampening can be achieved. This approach is obviously time consuming and labor intensive, resulting in unacceptably high processing and piece part costs.
Therefore, what is needed is a flocking apparatus, and a process thereby, which can uniformly apply flocking fibers to a spring clip such that the processing costs and time are minimized, and which enables the flocking fibers to be directly adhered to the spring clip to produce a flocked spring clip that is suitable for use in commercial production applications.